Tolerance in transgenic mice expressing major histocompatibility molecules extrathymically on pancreatic cells

Transgenic mice with defined expression of major histocompatibility complex (MHC) proteins provide novel systems for understanding the fundamental question of T cell tolerance to nonlymphoid self components. The MHC class II I-E and I-A and class I H-2K molecules expressed specifically on pancreatic islet or acinar cells serve as model self antigens. In these systems, transgenic proteins are not detected in the thymus or other lymphoid tissues. Yet mice are tolerant to the pancreatic MHC products in vivo; this tolerance is not induced by clonal deletion. These studies have been aided by monoclonal antibodies specific for I-E-reactive T cells and indicate that clonal anergy may be an important mechanism of tolerance to peripheral proteins.